How to Play Photosynthesis: Sunlight, Trees & Life Cycles
Photosynthesis is a spatial strategy game where the sun rotates around a shared forest. Trees collect light only when taller trees do not cast shadows over them, and light points fund the full seed-to-large-tree life cycle.
Photosynthesis phase: collect light
At the start of a round, the sun shines from its current side of the board. Each unshadowed tree produces light based on its size. A tree can cast a shadow across a number of spaces based on its height.
Life Cycle phase: spend light points
Players take turns spending light to buy pieces from their personal boards, plant seeds, grow seeds into small trees, grow trees to the next size or harvest/collect a large tree for a scoring token.
Each board space can normally activate once per turn
A space used as the origin or target of a life-cycle action cannot be repeatedly manipulated in the same turn in ways forbidden by the rulebook. For example, you cannot normally plant a seed and immediately grow it in the same turn.
Board position changes scoring value
When a large tree is harvested, take the top scoring token from the pile matching that board zone. More central fertile zones generally offer stronger scoring tokens but also attract more competition and shadow pressure.
The sun rotates after each round
Pass the first-player marker and move into the next sun angle. A position that was bright this round may be shadowed next round, so the forest’s economy changes predictably.
The standard game lasts three full sun revolutions
After three revolutions—18 rounds in the current base rules—the game ends. Add scoring-token points and the standard leftover-light conversion.
Publisher reference: Blue Orange Games: Photosynthesis. Checked September 21, 2026.